Tom Williams/CQ Roll Call(NEW YORK) — President-elect Donald Trump has named retired Lt. Gen. Michael Flynn as his National Security Adviser, according to senior Trump transition officials, rewarding one of his campaign’s most prominent allies with a major role as he seeks to fulfill his promise to better protect the country.

In the role, Flynn will consult with Trump on protecting the country’s citizens, key infrastructure and resources and sit on the National Security Council with Trump, Vice President-elect Mike Pence, the incoming secretaries of state, defense and energy, chairman of the joint chiefs of staff and other key officials.

Responsible for the country’s military and foreign policy efforts, Flynn will play a sizable role in shaping the Trump administration’s policies, including how to deliver on the campaign promise to “defeat ISIS and radical Islam.”

Flynn brings to the job nearly 30 years of military experience. He was a major surrogate and adviser on national security issues throughout Trump’s campaign, frequently appeared at rallies and became a regular figure on weekend news programs.

Flynn has also been viewed as a controversial figure in some circles. In February, Flynn received criticism for tweeting, “fear of Muslims is RATIONAL.”

He also served as director of the Defense Intelligence Agency from 2012 to 2014. Flynn left the position in 2012, claiming in an op-ed published in the New York Post that he was forced out for “calling our enemies radical jihadis.”

Though a registered Democrat, Flynn emerged from the DIA highly critical of President Obama and his administration’s approach to the Middle East.

In an interview with CNN last December, Flynn said the White House ignored intelligence reports that pointed to the eventual rise of ISIS, because it didn’t “meet a particular narrative the White House needed” when Obama was running for reelection in 2012.

The selection of Flynn is the third major appointment made by Trump since last week’s election. On Sunday he named Republican National Committee Chair Reince Priebus his chief of staff and former Breitbart News executive Steve Bannon his chief strategist and senior counselor.

The position Flynn will fill is not subject to Senate confirmation. Flynn replaces Susan Rice who has served as President Obama’s National Security Advisor since July 2013.